The Montreux Convention Regarding the Regime of the Straits is a 1936 agreement that gives Turkey control over the Bosporus and Dardanelles straits and regulates the transit of naval warships. The Convention guarantees the free passage of civilian vessels in peacetime, and restricts the passage of naval ships not belonging to Black Sea states. The terms of the Convention have been a source of controversy over the years, most notably about the Soviet Union's military access to the Mediterranean Sea.